Process of reclaiming used lubricating oil



Jan. 8, 1929. 1,698,257

G. L. CHERRY l PROCESS OF RECLAIMING USED LUBRICATING OIL Filed May 5,1926 H H II H II II I! an. aaaiiuai 0 I Patented Jan. 8, 1929.

UNITED STATES GEORGE L. CHERRY, OF LIBERTYVILLE,

ILLINOIS, ASSIG NOR TO THE LAVAL SEPARATOB COMPANY, NEW YORK, N. Y., ACORPORATION. OF NEW JERSEY.

/ 1 PROCESS OI BECLAIMING USED LUBRICATING OIL.

Application filed May '5,

My invention relates to the reclamation of.

used lubricating oil and is particularly applicable to the reclamationof used car axle oil.

5 This dirty oil consists of so tight an emulsion of water, very finedirt and oil that even when heated to about 210 F. for several days itshows no sign of separation.

The object of the invention is to so thoroughly remove impurities fromthe oil that itlwill be suitable for re-use in place of new 01 Attemptshave been made, without success, to recover this oil by adding solutionsof salts and alkalies.

I have found that the addition of from one to three per cent of analkali, Such as caustic soda, in a dry state, to the dirty oil, while itisheated to about 210 R, will cause, after 2 the soda has been dissolvedin the water press ent, a slow separation of most of the dirt and waterfrom the oil, which is left in such a condition that the remaining dirtand water may be easily removed by a centrifuge;

The process is not dependent for its'exe- 1 cution on the use of anyparticular apparatus, but the apparatus shown in elevation in theaccompanying drawing affords a means for carrying out the process withgreat elliciency. A closed steam-jacketed conical-bottomed treating tanka has, attached to its top, a relief valve 6 and an inwardly openingcheck valve 0. Through a pipe d steam may be supplied to the jacket,which is provided with a condensate outlet 6. At the apex'of theconical' bottom, there is provided a large sludge draw-01f pipe f with acontrolling valve g.

Entering the pipe f above the valve 9 is an oil inlet pipe It with avalve i, fed by a pump y from a sump tank k.

Within the treating tank, float Z supports a swinging draw-off pipem-leading, through a pipe n, with valve 0, to a centrifugal oilpurifier'p. From the pipen a branch 9 with a valve r leads to the sumptank 70.

A hot water inlet to the pipe n is provided through a pipe 8 with valvet.

The centrifugal separator has three outlets, the bottom one u, adaptedto discharge the heavy constituents, discharging into a pipe 4; leadingto the sewer; the middle one w, adapted to discharge the lightconstituent, discharging into a pipe as leading to a clean oil storagetank; and the upper one 3 being 1926. Serial naioass'z.

an overflow arranged to discharge into'the sump tank is. Y

On the side of the treating tank a is a series of try cocks z. A manholea with a tightcover is provided in the top of the tank to permit,examination of the inside of the tank..

A pipe 10 enters through the tank top, extends nearly to the bottom, andends in a horizontal radial nozzle 11 for a water jet to flush out anysolids that may collect on the bottom. A valve 12 controls the flow.

In order to carryout my process, the above described apparatus isoperated in, preferably, the following manner:

Dirty oil, as collected, is put into the sump tank is until there isenough for a batch. It is then pumped into tank a through pipe h andheated. When the temperature is nearly 210 F., the pump j is started andthe valve 0 opened enough to keep the inlet to the pump covered. Dryground caustic soda isnow poured slowly into the sump tank, wherein itmeets the stream from the pipe 9. The addition of soda is continueduntil about 1% per cent of soda by weight of oil, or about twelve poundsof caustic soda per 100 gallons of oil, has been added. (While some oilswill not need more than one per cent, others may need as much as threeper cent, though I have found 1 per cent suitable for many oils.) Thecirculation through the sump tank, pump, treating tank, etc., iscontinued until all the soda is dissolved and thoroughly mixed with theoil. The oil is then allowed to stay in the treating tank for from tento fourteen hours with the, temperature maintained in the neighborhoodof 210 F. At the end of that tinietherewill be found in' the bottom ofthe tank a layer of sludge,

above that a layer of water, and above that ture of oil and water toenter the centrifugal.

No exact ratio of the proportion of water to oil is necessary, but, aratios-of three to fi ve'- ity adapted for use'instead of new oil. The

float-supported swinging pipe permits drawing off all the oil withoutalso drawing off any of the sludge from the bottom of the tank, w

After all the oil has been drawn off and run through the oil purifier,the valve 9 may be opened and all the sludge and water allowed to escapeto the sewer; A'sudden flow of water from the jet 11 will wash out thelast of the sludge.

No fi res have been iven above for the rate of eed to the oil purifier,as that will depend on the make and size of the machine. I have foundthat a De Laval No. 300 machine can properly treat about twenty-fivegallons per hour of oil, anda No. 600 machine of the.

same make about seventy-five gallons per hour.

As stated in the preliminary remarks, I know that it is old to treatdirty oils with solutions of salts and alkalies. I have tried soda is aknown treating agent for use in the purification of contaminatedoil, andI made such solutions and even dry sodium chloride on the described oilwithout success while the above described process, evolved after muchexperimental work, has proven very successful and is now in regular use.

' While I prefer to use caustic soda as the V treating agent, certainother alkalies, such as caustic potash, are also efficient, and itisnotiintended, in claiming caustic soda, to exclude equivalents. Asolution of caustic no. claim, broadl to theuse of caustic soda or anyother a ali or treating agent, my

rocess involving the novel features particutaminated with water andsolids in order arly pointed out in the claims.

While I have given a certain temperature for treatment and certainproportions of reagents,"I do not wish to limit myself to precisely 210Frnor to proportions except in those claims where proportions aredistinctly specified, A temperature just below the boiling point ofwater and the specified proportions, however, have given excellentresults and seem to necessarily characterizethe most eflicient way ofexecuting the process. Good, though somewhat less efficient, results maybe obtained with other proportions of the reagent and at a temperatureas low as 180 F. at atmospheric pressure. In specifyin a temperatureapproximating or in the nel hborhood of 210 F., I do not mean to exc udea variation of five degrees or thereabouts from that precise temperatureat atmosphericpressure or any equivalent temperature at a differentpressure.

Having now fully described 'my invention,

what I claim and desire to protect by Letters Patent is:

1. The process of purifying used oil contaminated with water and solidsin order to reclaim it for re-use, which comprises heating the impureoil to not above approximately210 Rand mixing there'with caustic soda ina substantially dry state until the soda is dissolved and subsequentlyseparating the oil from the impurities.

2. The process of purifying used oil contaminated with water and solidsin order to reclaim it for re-use, which comprises heat.- ing the impureoil to not above approximately 210 F. and mixing with it caustic soda ina substantially dry state, settling to prec'ipitate the major part ofthe impurities and treating agent, and subjecting the oil to centrifugalforce 0 separate therefrom such portion of the treating agent as issuspended I therein.

3. The process of purifying used oil contaminated with water and solidsin order to reclaim it for re-use, which comprises heating the impureoil to not above approximately 210 F. and mixing with it caustic soda ina substantially dry state, settling to pre cipitate the major part ofthe impurities and treating agent, and washing and centrifugal lypurifying the oil. a 4. The process ofpurifying used oil contaminatedwith water and solids in order to reclaim it for re-use, which comprisesheating the impureoil to a temperature just below the boiling point ofwater and mixing with it caustic soda in a substantially dry state,settling to precipitate the major part of the impurlties and thetreating agent, and subjecting the oil to centrifugal force to sepa ratetherefrom the remainder of the impurities and treating agent.

5. The process of purifying'used oil conto reclaim it for re-use, whichcomprises heating the impure oil to not above approximately 210 F. andmixing withit not less than about one per cent of dry caustic soda,settling to precipitate the major part of the impurities and treatingagent, and subjecting the oil to centrifugal force to separate therefromthe remainder of the impurities tling to precipitate the major partof'the impurities and treating agent, and centrifugally purifying theoil.

7. The process of purifying used oil contaminated with water and solidsin order to reclaim it for re-use, which comprises heating the impureoil to a temperature just below the boiling point'of Water and mixingwith it not less than about one per cent. of caustic soda in asubstantially dry state, settling for not less than about eight hours,removing the supernatant, partially purified oil, washing it 'WithWater, and centrifugally separating the oil from the wash Water and theremaining impurities and treating agent. 1

8. That process of reclaiming used oil containing Water and solidimpurities Which comprises heating to nearly the boiling point of Water,dissolving caustic soda in a substantially dry state in the containedwater and mixing with the entire mass, keeping the mass hot Whileallowing settlement until the major-portion of the solid impurities isin a bottom sludge layer, a major portion of the oil in a top layer andsome of the water in an intermediate layer, drawing oi? the supernatantoil, adding clean water, and centrifugally removing the remaining tracesof solid impurities and caustic soda with the Water.

9. The process of purifying used'oil contaminated with Water and solidsin order to ing the impure oil to a temperature just below the boilingpoint of Water and mixing with it caustic soda in a substantially drystate until the soda is dissolved and subsequently separating theoil-from the impurities.

In testimony of which invention, I have hereunto set my hand, atChicago, Illinois, on this 1st day ofMa, 1926.

' E0. L. CHERRY.

